Book Image

Essential Statistics for Non-STEM Data Analysts

By : Rongpeng Li
Book Image

Essential Statistics for Non-STEM Data Analysts

By: Rongpeng Li

Overview of this book

Statistics remain the backbone of modern analysis tasks, helping you to interpret the results produced by data science pipelines. This book is a detailed guide covering the math and various statistical methods required for undertaking data science tasks. The book starts by showing you how to preprocess data and inspect distributions and correlations from a statistical perspective. You’ll then get to grips with the fundamentals of statistical analysis and apply its concepts to real-world datasets. As you advance, you’ll find out how statistical concepts emerge from different stages of data science pipelines, understand the summary of datasets in the language of statistics, and use it to build a solid foundation for robust data products such as explanatory models and predictive models. Once you’ve uncovered the working mechanism of data science algorithms, you’ll cover essential concepts for efficient data collection, cleaning, mining, visualization, and analysis. Finally, you’ll implement statistical methods in key machine learning tasks such as classification, regression, tree-based methods, and ensemble learning. By the end of this Essential Statistics for Non-STEM Data Analysts book, you’ll have learned how to build and present a self-contained, statistics-backed data product to meet your business goals.
Table of Contents (19 chapters)
1
Section 1: Getting Started with Statistics for Data Science
5
Section 2: Essentials of Statistical Analysis
10
Section 3: Statistics for Machine Learning
15
Section 4: Appendix

Revisiting bias, variance, and memorization

Ensemble methods can improve the result of regression or classification tasks in that they can be applied to a group of classifiers or regressors to help build a final, augmented model.

Since we are talking about performance, we must have a metric for improving performance. Ensemble methods are designed to either reduce the variance or the bias of the model. Sometimes, we want to reduce both to reach a balanced point somewhere on the bias-variance trade-off curve.

We mentioned the concepts of bias and variance several times in earlier chapters. To help you understand how the idea of ensemble learning originated, I will revisit these concepts from the perspective of data memorization.

Let's say the following schematic visualization represents the relationship between the training dataset and the real-world total dataset. The solid line shown in the following diagram separates the seen world and the unseen part:

...